It is well known to those skilled in the art that gelled or crosslinked water-soluble polymers are useful in enhanced oil recovery operations. They have been used to alter the permeability of underground formations in order to enhance the effectiveness of water flooding operations. Polymers along with an appropriate crosslinking system are injected in an aqueous solution into the formation. The polymers then permeate into a gel in the regions having the highest water permeability. Any fluids injected into the formation in subsequent water flooding operations, will then be diverted away from the regions in which the gel formed to areas of the formation now having a higher water permeability.
Although this technique is effective in enhancing hydrocarbon production, it does have problems. The primary one being that water-soluble polymers and conventional crosslinking agents gel fairly quickly after being injected into the formation at an elevated temperatures. Quite often only the regions near the well bore are treated, since the polymers and conventional crosslinking agent gel before they have an opportunity to percolate very far into the formation.
It would therefore be a valuable contribution to the art to develop an organic crosslinking system which had a delayed gelation rate to permit greater penetration into the formation of the water-soluble polymer and crosslinking agent before gelation occurs.
Thus, it is an object of the present invention to provide a novel crosslinking system with a delayed gelation rate in high temperature.
It is a further object of the present invention to provide novel gels formed with said novel crosslinking system and water-soluble polymers.
Other aspects and objects of this invention will become apparent here and after as the invention is more fully described in the following summary of the invention and detailed description of the invention, examples, and claims.